The broad goal of this research is to continue studies of inherited deficiencies of human carbonic anhydrases (CAs) in order to define the physiological roles of individual members of this gene family, to decipher their genetic and physiologic interrelationships, and to understand their individual importance in health and disease. For this project period there are five specific aims: 1) Complete studies defining the biochemical and molecular genetics of carbonic anhydrase II deficiency. (CA II deficiency is the basis of the newly classified inborn error producing osteopetrosis, renal tubular acidosis, and brain calcification.) 2) Complete the biochemical and molecular genetics of carbonic anhydrase IV. (CA IV is the membrane anchored CA in kidney and lung and on the luminal surface of capillary endothelial cells). 3) Produce a murine model for CA IV deficiency by targeted mutagenesis in ES cells. 4) Define the biochemical and molecular genetics of CA V. (CA V is the nuclear-encoded, mitochondrial CA in liver and muscle.) 5) Produce a murine model of CA V deficiency by targeted mutagenesis in ES cells. Carbonic anhydrases are purified, characterized, subjected to microsequencing, and used to prepare polyclonal antibodies for metabolic labeling and biosynthetic studies. The cDNA and genomic clones are isolated to determine the genomic organization, the intronic sequences surrounding intron/exon boundaries, the chromosomal localization, and the nature of the mutations underlying altered expression of the carbonic anhydrase genes. Targeted mutagenesis in ES cells will be exploited to produce animal models of selected CA deficiencies.